Photosensitive resin compositions for color filter applications

ABSTRACT

New polymers, compositions comprising these polymers, and methods of using these compositions are provided. The polymers comprise styrene and maleic anhydride monomers with at least some of the maleic anhydride monomers having certain functional groups bonded thereto. Preferred functional groups include those derived from adhesion promoters (e.g., 2-aminophenol), photoinitiators (e.g., 4-aminoacetophenone), and solubilizers (e.g., 4-aminobenzoic acid). The polymers can be incorporated according to conventional processes into compositions which are then used to form a color filter to be used in a liquid crystal display. The final color filter has a high resolution, is highly resistant to solvents typically used in the color filter manufacturing process, is strongly adhered to the color filter substrate, has superior optical clarity, is highly soluble in a wide range of alkali developers, and has excellent heat and UV light stability.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.09/640,227 filed Aug. 16, 2000, now abandoned incorporated by referenceherein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is broadly concerned with new polymers,compositions comprising these polymers, and methods of using thesecompositions to form a color filter for use in a liquid crystal display.More particularly, the polymers comprise recurring monomers of styreneand maleic anhydride with amino functional groups (e.g.,4-aminoacetophenone, 2-aminophenol, 4-aminobenzoic acid) bonded to atleast some of the maleic anhydride monomers.

2. Description of the Prior Art

Color filters are commonly used in liquid crystal display panels,imaging devices, and similar items, and are generally comprise a mosaicof pixels or as a striped pattern. A liquid crystal display is usuallyproduced by forming a multicolor image layer on a transparent glasssubstrate. The multicolor image layer typically contains red, green, andblue picture elements and, in some cases, also includes a black-coloredor black-shaded matrix. A protective layer is then formed on themulticolored image layer, and a transparent conductive layer issubsequently formed on the protective layer, usually by sputtering ofindium-tin-oxide (ITO). In the case of a super twisted nematic(STN)-type or a ferroelectric liquid crystal-type panel, the transparentconductive layer is further processed through photolithography to yielda color filter equipped with a transparent electrode, after which anoriented film is formed on the transparent electrode. That substrate andanother similarly-formed substrate are sealed together with a gaptherebetween, with liquid crystals being poured between the twosubstrates to yield the display panel.

In the past, the protective layer has been formed on the multicolorimage layer for a variety of reasons. For example, the protective layerprotects the multicolor image layer from various chemicals (e.g.,solvents for the photoresist, acidic etching solutions, basic resistrelease solutions, solvents for the oriented film coating) used in thephotolithographic process carried out to produce the transparentconductive layer. Furthermore, the protective layer gives flatness tothe multicolor image layer and assists in maintaining the gap betweenthe two substrates into which the liquid crystals are poured. It isimportant that the protective layer is transparent (without cloudinessor turbidness) in the visible light region, and that the layer isstrongly adhered to both the multicolor image layer and to thesubstrate.

Recently, there has been a demand to remove the protective layer inorder to insure sealing in the non-image portions. As a result, thecolor layer must be formulated to function in the same manner as theprotective layer. Photosensitive resin-type binders are generally usedas binders for the color layer in order to enable the layer to meet theabove-described requirements. The most popular of these binder resinsare those which can be crosslinked by a photo-induced reaction whenexposed to UV light. The unexposed portions can then be developed inaqueous alkali solutions which are safe and are the environmentallypreferred solutions. The resin is thereafter further cured by heating togive increased chemical resistance.

Color filters containing such a photosensitive resin are prepared bydispersing pigments in the resin. The resin/pigment system also includesdispersing agents which stabilize the pigment dispersion, surfactantswhich improve the coating smoothness, an addition-polymerizable monomerhaving an ethylenically unsaturated double bond which improvesphoto-crosslinking density, and photoinitators for catalyzing thephoto-crosslinking reaction.

The color filters must have several other properties in addition to theproperties discussed above with respect to the protective layer. Forexample, the color filter must be able to define a clear pattern ofpixels or stripes at small dimensions (e.g., pixel sizes as small as 5μm). To produce a distinct image without blurriness or fuzziness, thepixels must also be of uniform size and thickness and have straight,clean edges without roughness or pigment residue. Furthermore, thepigments in the composition used in forming the color filter must remaindispersed in the composition over long periods of time, and thecomposition must also maintain color purity even after prolongedexposure to light. That is, there should be little or no yellowing ordiscoloration of either the photosensitive resin or the pigments of thecomposition. Finally, the resulting color filter must be readilyprocessible by standard photolithographic techniques (e.g., the colorfilter should not require a broadband UV exposure of over 600millijoules).

Examples of known photosensitive resins for color filters are describedin U.S. Pat. No. 5,445,919 to Wakata et al., U.S. Pat. No. 5,514,502 toWakata et al., and U.S. Pat. No. 5,650,263 to Wakata et al. Thesepatents describe photopolymerizable compositions which comprise aphotopolymerization initiator or a photopolymerization initiator system,an addition-polymerizable monomer having at least one ethylenicallyunsaturated double bond, and a resin obtained by reaction of ananhydride-containing copolymer having a number average molecular weightof 500 to 30,000. This resin has primary amines in a ratio to thecopolymer at 0.1 to 1.0 equivalent per equivalent of the anhydride inthe copolymer.

Another resin of this type is disclosed in U.S. Pat. No. 5,641,594 toKudo et al. This composition includes: a polymer having alcoholic orphenolic hydroxyl groups; a compound capable of producing a nitrene whenirradiated with an actinic radiation; a pigment; and a solvent. Thecomposition can further contain a heat crosslinking agent and/or acompound having a polymerizable double bond in addition to the aboveingredients.

The compositions described in the '919, '502, '263, and '594 areinadequate for developing color filters with sufficient resolution andsmall pixel size required in modern high-resolution devices. While thesecompositions may satisfy some of the requirements described above, noneof these resins can meet all color filter needs, especially at 2-4 μmresolution. Furthermore, these compositions require the use of athermal-crosslinking agent such as tris(acryloloxyethyl) isocyanurate,diisocyanates, or methacrylate melamine compounds. While such additivescan improve film hardness and chemical resistance, they are difficult touse and environmentally unfriendly. Isocanates in particular are knowncarcinogens.

U.S. Pat. No. 5,998,091 to Suzuki describes the synthesis of variousmonomers, that may be useful for the synthesis of a photosensitive resinwhich can be used to manufacture color filter materials. While thispatent discloses various monomer structures which aid in adhesion to thesubstrate, alkaline solubility, and pigment dispersion stability, itdoes not disclose a final polymer composition which can meet the needsdescribed above. In particular, this patent does not disclose acomposition which has high photosensitivity, film hardness, and chemicalresistance required for color filter materials.

European Patent Application No. 780,731 describes a photosensitive resinwhich incorporates a phosphoric methacrylate resin, in addition to thephotosensitive resin to improve solubility in alkali developer. However,this system discloses nonhomogenous intermixing of the two binder resinswhich can result in uneven develop characteristics across the entirecolor filter panel. This is especially true at 2-4 μm pixel sizes, whereuniform development is very critical.

U.S. Pat. No. 6,007,966 to Lin describes an alkali-developable, negativeacting photosensitive composition which comprises a polymer binder, aphotoinitiator, and an unsaturated photomonomer. The polymer binder isprepared from a reaction among a styrene-maleic anhydride resincontaining repeating units of styrene and anhydride groups, anunsaturated compound containing at least one hydroxy group and at leastthree acrylic groups, and a saturated alcohol. This resin system is notoptimized for high resolution color filter applications, instead it isdesigned for the manufacture of printed circuit boards, which have largefeature sizes. Thus, this system cannot be used to produce a colorfilter pattern with clear 2-4 μm resolution.

U.S. Pat. No. 6,051,367 to Kunita et al. a photopolymerizablecomposition which comprises a compound having one or moreaddition-polymerizable ethylenically unsaturated bonds and a specificoxime ether compound. However, this compound produces a film whereunexposed areas are not developable in aqueous alkali solutions, butinstead require a solvent developer. Furthermore, this composition isnot suitable for achieving 2-4 μm high resolution patterns.

U.S. Pat. No. 6,027,856 to Nozaki et al. describes a negative-typeresist composition which is developable in a basic aqueous solution andcomprises a film-formable, basic aqueous solution-soluble polymer withan alkali-soluble group. The composition also includes a compound withan allyl alcohol structure and a photoacid generator which whendecomposed by absorption of image-forming radiation causes the compoundwith an allyl alcohol structure to become a protecting group for thealkali-soluble group, as well as a resist pattern-forming process whichemploys it. A basic aqueous solution can be used as the developingsolution, however, the photoacid generator used in this compositionrequires an extra hotplate bake process step over conventional colorfilter materials. Also, as this composition is a negative photoresist,it is not formulated to support pigment dispersions which are used incolor filter materials.

SUMMARY OF THE INVENTION

The present invention overcomes the problems of the prior art by broadlyproviding new polymers, compositions comprising these polymers, andmethods of using these compositions to form color filters for use in aliquid crystal display.

In more detail, the polymers according to the invention comprise variousfunctional groups (e.g., adhesion promoting groups, photoinitiatinggroups, solubilizing groups) grafted onto or bonded to at least some ofthe maleic anhydride monomers of a precursor polymer comprising styreneand maleic anhydride monomers. The precursor polymers can include othermonomers in addition to styrene and maleic anhydride, but it ispreferred that a styrene-maleic anhydride (SMA) copolymer be utilized.Preferably, the molar ratio of styrene:maleic anhydride in the precursorpolymer is from about 1:1 to about 4:1, preferably from about 2:1 toabout 4:1, and more preferably about 3:1. The preferred functionalgroups comprise an aryl moiety with at least one amino group bondedthereto.

The inventive polymer is formed by reacting the selected functionalgroup(s) (either one at a time or simultaneously) with the precursorpolymer under conditions to cause at least some of the maleic anhydriderings (preferably at least about 60% of the rings) of the precursorpolymer to break and nitrogen atoms from at least one of the respectiveamino groups to bond to the carbon atom of one of the carbonyl groups onthe resulting maleic anhydride moiety. Thus, polymers formed accordingto the invention will comprise recurring monomers of the formulas

wherein R₁ is a compound selected from the group consisting of —OH andcompounds represented by the following formulas:

 wherein in the above structural formulas:

each R₂ is individually selected from the group consisting of hydrogen,—NH₂, and —NH;

x is a number ranging from about 1-5, and preferably from about 1-2;

at least one R₂ is —NH and the at least one —NH is bonded to one of thecarbon atoms labeled with a (1) or a (2);

each R₃ is individually selected from the group consisting of hydrogen,—NH₂, and —NH;

y is a number ranging from about 0-5, and preferably from about 1-2; and

at least one R₃ is —NH and the at least one —NH is bonded to one of thecarbon atoms labeled with a (1) or a (2),

with at least one R₁ being one of the compounds represented by the aboveformulas (i.e., a compound other than an —OH group).

In a particularly preferred embodiment, the polymer comprises recurringmonomers of at least one of the structures of each class represented inthe above formulas (i.e., at least one adhesion promoter, at least onephotoinitiator, and at least one solubilizer). Even more preferably, thepolymers include recurring monomers of each of the following formulas(i.e., the polymers include 4-aminoacetophenone, 2-aminophenol, and4-aminobenzoic acid each individually reacted with at least one of themaleic anhydride monomers of the particular polymer).

In an alternate embodiment, the polymer comprises a photoinitiatorbonded thereto. The molar ratio of photoinitiator:maleic anhydrideshould be from about 1:20 to about 1:1.45, preferably from about 1:20 toabout 1:2.5, and more preferably from about 1:10 to about 1:5. Thephotoinitiator is useful because it improves the degree of crosslinkingof color filter compositions including the inventive polymers. Enhancedcrosslinking improves pattern resolution, substrate adhesion, filmhardness, and chemical resistance of films or layers formed from suchfilter compositions. A particularly preferred monomer comprising amaleic anhydride moiety reacted with a photoinitiator is represented bythe formula

The polymer preferably further comprises an adhesion promoting groupbonded thereto. This is beneficial for forming a pigmented color filtercomposition which will strongly adhere to the substrate of the liquidcrystal display panel thus improving pattern resolution and edgesharpness. The adhesion promoting group should comprise from about 2-50%by weight, preferably from about 2-25% by weight, and more preferablyfrom about 4-10% by weight of the polymer, with the percentage by weightbeing based upon the total weight of the polymer taken as 100% by weightand referring only to the weight attributable to the adhesion promotingportion of the polymer (i.e., not including the weight of the maleicanhydride moiety to which the adhesion promotor is bonded). Thepreferred monomer comprising a maleic anhydride moiety reacted with anadhesion promoter is represented by formula

It is also preferred that the polymer comprise a functional group bondedthereto which acts to improve the solubility of compositions includingthe inventive polymer in aqueous alkali developers such astetramethylammonium hydroxide, potassium hydroxide, and sodium carbonatedevelopers. Improved solubility in the developer will lead to improvedpattern resolution and edge sharpness of the color filter. Thissolubility-improving monomer preferably comprises from about 2-50% byweight, preferably from about 2-20% by weight, and more preferably fromabout 4-10% by weight, with the percentages by weight being based uponthe total weight of the polymer taken as 100% by weight and referringonly to the weight attributable to the solubilizing portion of thepolymer (i.e., not including the weight of the maleic anhydride moietyto which the solubilizer is bonded). A particularly preferred monomercomprising a maleic anhydride moiety reacted with a solubilizingcompound is represented by the formula

The polymers formed according to the invention have an average molecularweight of from about 7,000-13,000 Daltons, and preferably from about9,000-11,000 Daltons. It will be appreciated that these polymers can beincorporated into compositions which are used to form the pixels on animage layer of a liquid crystal display. Such compositions can be formedaccording to known preparation procedures. For example, a pigment slurrycan be prepared by mixing the desired types and concentrations ofpigments with dispersants and/or solvents for the particular pigments. Acolored pigment mother liquor can be prepared by mixing a binder resinsolution comprising the inventive polymer with the pigment slurry. Theresulting mixture is then ground, and a surfactant solution is mixedtherewith. The pigment mother liquor is mixed with the desired curingagents, solvents, surfactants, and any other desired ingredientsfollowed by filtering of the mixture to an average particle size of lessthan about 0.2 μm.

The resulting colored, photosensitive coating composition can then beapplied to a substrate (e.g., glass, silicon, ITO glass, color filterlayers, etc.) by conventional processes (such as by spin-coating atabout 1000 rpm followed by baking on a hotplate at about 100° C.). Thecoated film is exposed through a mask to light at the desired wavelength(e.g., from about 200-500 nm) followed by developing of the film,preferably in a basic developer (e.g., MF312-D27, available from ShipleyCompany). Finally, the developed film is cured on a hotplate undervacuum at a temperature of from about 150-210° C., and the process isrepeated as necessary with different pigment colors to obtaindifferently colored pixels as desired for the particular application(e.g., red, green, and blue pixels), and a protective layer can beapplied to the final image layer and cured.

Advantageously, coating compositions utilizing the polymers of theinvention give a solvent resistance test result (as defined in Example7) of less than about 5, preferably less than about 3, and morepreferably less than about 2 when PGMEA is used as the solvent. Thus,the resulting films are highly solvent resistant and do not require theuse of additional thermal crosslinking agents such as diioscyanateswhich are hazardous to the user as well as to the environment.

Also, a color filter formed according to the invention comprising animage layer having a thickness of about 1.5 μm will transmit from about70-95%, preferably from about 80-95%, and more preferably from about85-90% of light at a wavelength of from about 400-700 nm. Additionally,the inventive color filters will have a resolution of less than about 5μm, preferably from about 2-4 μm, and more preferably from about 1-2 μm,as determined by a scanning electron microscope. A film formed fromcompositions comprising the inventive polymers and deposited and curedon a substrate will have a pencil hardness (as determined by JIS K5400)of at least about 4H, and preferably at least about 8H.

Furthermore, films formed from the inventive compositions are highlysoluble in alkali developers and exhibit essentially no discoloration oryellowing when exposed to UV light for up to about 2 million lux-hoursor when exposed to curing temperatures for time periods of up to about 7hours. Finally, films formed with the inventive compositions adherestrongly to substrate surfaces and exhibit excellent flatness even overtopographical surfaces.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES

The following examples set forth preferred methods in accordance withthe invention. It is to be understood, however, that these examples areprovided by way of illustration and nothing therein should be taken as alimitation upon the overall scope of the invention.

Example 1 Binder Resin Synthesis

In this example, 300 g of poly(styrene-co-maleic anhydride) (SMA) weredissolved in 1,000 g of propylene glycol methyl ether acetate (PGMEA) toform an SMA polymer solution. The molar ratio of styrene to maleicanhydride was 3:1, and the molecular weight of the polymer was about11,000 Daltons.

Next, 45.62 g (337.5 mmoles) of 4-aminoacetophenone were transferredfrom a flask to a 3,000 mL glass flask containing 1,200 g of the SMApolymer solution. PGMEA (32 g) was used to rinse residual4-aminoacetophenone from the flask in which it was stored. The reactionof grafting the amino group of the 4-aminoacetophenone to the anhydridegroup of the polymer was carried out for 24 hours at ambient conditionswhile stirring and under nitrogen. PGMEA (32 g) and 14.73 g (135.0mmoles) of 2-aminophenol were added to the reaction mixture, and thereaction was continued for 8 more hours. Next, 10.54 g (76.0 mmoles) of4-aminobenzoic acid and 32 g of PGMEA were added to the mixture, and thereaction was continued for another 48 hours.

Example 2 Binder Resin Synthesis

In this example, 1,200 g of the SMA polymer solution prepared in Example1 were mixed with the following compounds in a 3,000 mL glass flask:45.62 g (337.5 mmoles) of 4-aminoacetophenone; 14.73 g (135.0 mmoles) of2-aminophenol; and 10.54 g (76.9 mmoles) of 4-aminobenzoic acid. Theflask was then rinsed with 96 g of PGMEA, and nitrogen was introducedinto the flask. The reaction was carried out for 72 hours at ambientconditions while stirring. Subsequent analysis by infrared spectroscopyshowed that the simultaneous reaction of SMA with the 3 amino compoundsas described here gave the same binder resin composition as was obtainedin Example 1 where the amino compounds were reacted sequentially withthe SMA polymer.

Example 3 Binder Resin Synthesis

In this example, 300 g of SMA were dissolved in 1,000 g of cyclohexanoneto form an SMA polymer solution. The molar ratio of styrene to maleicanhydride was 3:1, and the molecular weight of the polymer was about11,000 Daltons.

Next, 1,200 g of the SMA polymer solution were mixed with the followingcompounds in a 3,000 mL glass flask: 27.4 g (202.7 mmoles) of4-aminoacetophenone; 14.76 g (135.3 mmoles) of 2-aminophenol; and 27.8 g(202.8 mmoles) of 4-aminobenzoic acid. A total of 96 g of cyclohexanonewas used to rinse the residual amino compounds from their respectiveflasks, and nitrogen was introduced into the 3,000 mL flask. Thereaction of grafting the amino groups to the respective anhydride groupsof the polymer was carried out for 72 hours under ambient conditionswhile stirring.

Example 4 Color Filter Coating Formulation, Deposition, and Patterning

Solsperse 22000 dispersant (3.06 g, available from Zeneca) and Solsperse5000 dispersant (1.52 g, also available from Zeneca) were dissolved in104 g of methyl ethyl ketone (MEK). To the resulting of the dispersion,40.78 g of BASF L9361 green pigment and 10.21 g of yellow highresolution (HR) pigment (available from Dominion Color Corporation) wereadded while stirring to form a first solution. A second solutioncontaining 74.37 g Solsperse 24000 (available from Zeneca) incyclohexanone and PGMEA (solvent weight ratio of 1:1 and a solidscontent of 18% by weight) was mixed with the first solution. Theresulting pigment mixture was ground into a slurry for 1 hour in a millcontaining glass beads. The pigment slurry was stored for at least 12hours in ambient conditions prior to use.

A mother liquor was formed by mixing 65 g of the binder resin solutionprepared in Example 3 with 100 g of the green pigment slurry. Theresulting mixture was ground for 1 hour in a mill, and a surfactantsolution containing 0.2 g FC171 fluorosurfactant (available from 3M) in55 g of MEK was added to the mill. The green pigment mother liquor wasthen ground for another ½ hour.

Next, 100 g of the green pigment mother liquor were mixed with thefollowing compounds for 1 hour under ambient conditions: 0.05 g of FC430fluorosurfactant (available from 3M); 5 g of dipentaerythritolpentacrylate esters (DPEPA, obtained from Sartomer under the nameSR399); 1 g of octyl para-(dimethylamino)benzoate (ODAB); 25 g of MEK; 3g of Irgacure 784 (available from Ciba); and 1 g of Irgacure 369 (alsoavailable from Ciba). The final photosensitive green coating wasfiltered through a filter having a pore size of 0.21 μm.

The filtered photosensitive green coating was then spin-coated at 850rpm for 60 seconds onto a 4-inch silicon wafer to form a film which wasthen soft-baked on a hotplate (i.e., contacting the hotplate, but withno vacuum being applied) at 100° C. for 60 seconds. Using an I-linestepper, the film was exposed to 600 mJ/cm² of energy. The exposed greenresin film was developed by dipping in a basic developer (MF312-D227,available from Shipley) for 25 seconds followed by immersing indeionized water for 20-25 seconds, rinsing with deionized water for20-25 seconds, and finally curing for 10 minutes on a hotplate undervacuum at 250° C. The maximum transmittance of the green color filter(determined prior to developing of the film) at a light wavelength ofabout 560 nm was about 85% at a film thickness of 1.5 μm.

Properties of the green photosensitive coating were determined by usingan optical microscope (500×) to view a field halfway between the centerand the edge of the wafer. From these properties, the resolution (i.e.,the smallest pixels achieved on the glass round) was determined to beabout 2 μm. These data are recorded in Table 1.

TABLE 1 PROPERTY MINIMUM MAXIMUM L/S Pair^(a) 1 μm 2 μm Pixel Array^(b)1 μm 3 μm Hole Array^(c) 1 μm 3 μm Scum^(d) none none Isolated Residuenone none Thickness^(e) 1.45 μm^(f) 1.55 μm^(f) ^(a)Line-space pair.^(b)Complete and intact 8 × 8 array of pixels. ^(c)Complete 8 × 8 arrayof holes free of film all the way to the substrate. ^(d)Defined as acontinuous residue that bridges the gap between pixels. ^(e)Measuredusing a Alphastep 200 profilometer. ^(f)Average thickness ofmeasurements at the following locations on wafer: at about the center ofthe wafer; about 1/3 of the way from the center to the wafer edge; andabout 2/3 of the way from the center to the wafer edge

Example 5 Comparative Example

This test was conducted to compare a green color filter coating usingunmodified SMA as the binder and dissolved amino compounds as thecoating additives (i.e., no pre-reaction of the SMA and the aminocompounds) to the green color filter coating prepared in Example 3.

The SMA polymer solution (65 g) prepared in Example 1 was mixed with 100g of the green pigment slurry prepared in Example 4 to form a motherliquor. The solution was ground for 1 hour in a mill, and a surfactantsolution containing 0.2 g FC171 in 55 g MEK was added to the mill. Thegreen pigment mother liquor was ground for another ½ hour.

Next, 100 g of the green pigment mother liquor were mixed with thefollowing compounds for 1 hour under ambient conditions: 0.05 g of FC430fluorosurfactant; 5 g of DPEPA; 1 g of Irgacure 369; 0.9862 g of4-aminoacetophenone; 0.3206 g of 2-aminophenol; and 0.2273 g of4-aminobenzoic acid. The final green photosensitive material wasfiltered through a filter having a pore size of 0.2 μm.

The filtered photosensitive green coating was spin-coated onto a 3-inchglass round to form a film which was soft-baked on a hotplate at 100° C.After exposure through a quartz mask on an I-line stepper for about 2minutes, the exposed green resin film was dipped into a developer(MF312-D27) for 20-40 seconds. The green resin film showed nodissolution selectivity between the exposed and unexposed areas and didnot develop. This demonstrated that grafting of 4-aminoacetophenone,2-aminophenol, and 4-aminobenzoic acid to SMA was necessary to form apatternable color filter coating.

Example 6 Comparative Example

This test was conducted to compare a green color filter coating usingSMA modified with 2-aminophenol and 4-aminobenzoic acid as the binderand dissolved 4-aminoacetophenone as the coating additive to the greencolor filter coating prepared in Example 3.

The SMA polymer solution (120 g) prepared in Example 1 was mixed withthe following compounds in a 250 mL glass flask: 1.47 g (13.53 mmoles)of 2-aminophenol; and 1.05 g (20.28 mmoles) of 4-aminobenzoic acid. Theflask was then rinsed with 9.6 g of PGMEA, and nitrogen was introducedinto the flask. The reaction of grafting the amino groups to therespective anhydride groups of the polymer was carried out for 72 hoursunder ambient conditions while stirring to form a polymer bindersolution.

A mother liquor was formed by mixing 65 g of the polymer binder solutionwith 100 g of the green pigment slurry prepared in Example 4. Thesolution was ground for 1 hour in a mill, and a surfactant solutioncontaining 0.2 g FC171 in 55 g MEK was added to the mill. The greenpigment mother liquor was ground for another ½ hour.

Next, 100 g of the green pigment mother liquor were mixed with thefollowing compounds under ambient conditions: 0.05 g of FC430fluorosurfactant; 5 g of DPEPA; 1 g of ODAB; 25 g of MEK; 3 g ofIrgacure 784; 1 g of Irgacure 369; and 0.9862 g of 4-aminoacetophenone.The final photosensitive green coating was filtered through a filterhaving a pore size of 0.2 μm.

The filter photosensitive coating was spin-coated on a 3-inch glassround to form a film which was soft-baked on a hotplate at 100° C. Afterexposing the coated film through a quartz mask using an I-line stepperat 300-1000 mj/cm², the exposed green resin film was dipped in adeveloper (MF312-D27) for 20-40 seconds. The green resin film showedvery poor dissolution selectivity between the exposed and unexposedareas. The poor development characteristics demonstrated that grafting4-aminoacetophenone to SMA prior to formulation and coating wasnecessary to produce a patternable color filter coating.

Example 7 Preparation of Red Color Filter

A red color filter coating was formulated by mixing 141.9 g of PGMEA,91.9 g of Disperbyk 182 (available from BYK), 5.1 g of dipentaerythritolpentacrylate ester (DPEPA), 33.7 g of the binder resin solution preparedin Example 2, 33.3 g of a red pigment (3B-RF, available from CIBA), and16.1 g of a yellow HR pigment (available from Dominion ColorCorporation). This solution was stirred for 10 minutes and added to agrinding mill which was then rinsed will 40 g of PGMEA. Grinding wascarried out for one hour.

A second solution was prepared by mixing 9.5 g of PGMEA, 15.3 g ofDPEPA, and 101.1 g of the binder resin solution prepared in Example 3.This solution was added to the mill containing the red pigment solutionprepared above. Next, 30 g of PGMEA was used to rinse the mill. A motherliquor was formed after grinding for one hour. The red pigment motherliquor (55 g) was mixed with the following compounds for one hour underambient conditions: 0.21 g of ODAB; 17.9 g of PGMEA; 1.49 g of Irgacure784; and 0.51 g of Irgacure 369. The final photosensitive red coatingwas filter through a filter having a pore size of 0.20 μm.

Example 8 Solvent Resistance Test

The solvent resistance test is performed by spin-coating a filtercoating onto a glass round at 1000 rpm for 90 seconds. The coated glassround is then baked on a hotplate for 60 seconds followed by exposure atabout 500 millijoules. After exposure, the coated round is cured in anoven at 190° C. for one hour. The color (i.e., absorbance) of the curedcoating is measured with a spectrophotometer across the visible spectrum(400-700 nm). The round is then placed in a solvent for 5 minutes afterwhich it is rinsed with water and dried with high-pressure air. Thecolor is measured again with a spectrophotometer across the visiblespectrum. The difference in color is calculated as a ΔE*ab value asdescribed by Gunter Wyszecki and W. S. Stiles in Color Science Conceptsand Methods, Quantitative Data and Formulae. Wiley & Sons, 2d ed., pp.166-168 (1982).

The solvent resistance test was carried out on the inventive green colorfilter coating formulated in Example 4 and the red color filter coatingprepared in Example 7. The results from these tests are set forth inTable 2.

TABLE 2 PGMEA NMP^(a) Acetone Developer^(b) green 0.55 2.71 1.74 1.04red 1.68 0.40 1.41 0.57 ^(a)N-methyl-2-pyrrolidone. ^(b)A commercialtetramethyl ammonium hydroxide-based photoresist developer.

We claim:
 1. The combination of: a substrate; and an image layercomprising a matrix of pixels, said image layer being deposited on saidsubstrate and said pixels being formed from a composition comprising apolymer which comprises recurring monomers of the formulas

wherein R₁ is selected from the group consisting of —OH groups and thoserepresented by the following formulas:

 where: each R₂ is individually selected from the group consisting ofhydrogen, —NH₂, and —NH; x is a number ranging from 1-5; at least one R₂is —NH and said at least one —NH is bonded to one of the carbon atomslabeled with a (1) or a (2); each R₃ is individually selected from thegroup consisting of hydrogen, —NH₂, and —NH; and y is a number rangingfrom 0-5, with there being at least one R₃ which is —NH and said atleast one —NH is bonded to one of the carbon atoms labeled with a (1) ora (2), at least one R₁ being represented by the above formulas; and saidimage layer transimitting from about 70-95% of light at a wavelength offrom about 400-700 nm when having a thickness of about 1.5 μm.
 2. Thecombination of claim 1, wherein said polymer comprises recurringmonomers of the formulas

wherein R₁ is selected from the group consisting of —OH groups and thoserepresented by the following formulas:

 where: each R₂ is individually selected from the group consisting ofhydrogen, —NH₂, and —NH; x is a number ranging from 1-5; and at leastone R₂ is —NH and said at least one —NH is bonded to one of the carbonatoms labeled with a (1) or a (2), and there being at least one of eachof said R₁ present in said polymer.
 3. The combination of claim 1,wherein said polymer comprises recurring monomers of the formulas


4. The combination of claim 1, wherein the molecular weight of saidpolymer is from about 7,000-13,000 Daltons.
 5. The combination of claim1, wherein said polymer comprises from about 5-70% by weight of aphotoinitiating group bonded to the Scheme B monomers, said percentageby weight being based upon the total weight of polymer taken as 100% byweight and being only the weight attributable to the photoinitiatinggroup.
 6. The combination of claim 5, wherein said photoinitiating groupbonded to a Scheme B monomer is represented by the formula


7. The combination of claim 1, wherein said polymer comprises from about2-50% by weight of a group bonded to the Scheme B monomers for improvingthe adhesion to a substrate of compositions containing said polymer,said percentage by weight being based upon the total weight of thepolymer taken as 100% by weight and being only the weight attributableto said adhesion-improving group.
 8. The combination of claim 7, whereinsaid adhesion-improving group bonded to a Scheme B monomer isrepresented by the formula


9. The combination of claim 1, wherein said polymer comprises from about2-50% by weight of a group bonded to the Scheme B monomers for improvingthe solubility in alkali developing solutions of compositions containingsaid polymer, said percentage by weight being based upon the totalweight of the polymer taken as 100% by weight and being only the weightattributable to the solubility-improving group.
 10. The combination ofclaim 9, wherein said solubility-improving group bonded to a Scheme Bmonomer is represented by the formula


11. The combination of claim 1, wherein said substrate is formed ofglass.
 12. The combination of claim 1, wherein said image layercomprises a matrix of a plurality of differently colored pixels.
 13. Thecombination of claim 12, wherein said image layer comprises a matrix ofat least red, green, blue pixels.
 14. The combination of claim 1, saidfilter further comprising a cured protective layer deposited on saidimage layer.
 15. The combination of claim 1, wherein said image layerhas a resolution of less than about 5 μm.
 16. The combination of claim1, wherein said composition gives a solvent resistance test result ofless than about 5 when propylene glycol methyl ether acetate is used asthe solvent.
 17. The combination of claim 1, wherein said compositionwhen formed into a cured film has a pencil hardness of at least about2B.
 18. The combination of claim 1, wherein when said image layer has athickness of about 1.5 μm, said image layer transmits from about 70-95%of light at a wavelength of from about 400-700 nm.